P051D code meaning
Crankcase Pressure Sensor A Circuit High
Powertrain system Generic code P05xx codes Check engine light
What P051D means
The crankcase pressure sensor measures pressure in the crankcase ventilation (PCV) against atmosphere; Ford's EcoBoost engines use it for the disconnection check P04DB, which needs a sound sensor. P051D means the signal is too high – Ford sets it above 4.56 V for 5 s. Typical is a signal shorted to 5 V or battery voltage, an open sensor ground, or an open signal pulled up. A real excess pressure in the crankcase does not set P051D.
P051D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P051D
- Check engine light on
- Usually no change in driving
- Disconnection check P04DB suspended
Common causes of P051D
- Most likelySensor ground open
- PossibleSignal line shorted to positive
- PossibleSensor faulty
- Less likelyEngine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Crankcase pressure sensorSensor wiringEngine control module
What each part of P051D means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 1D | The exact fault in that area. |
What to do next
- Note P051D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P051D
What does P051D mean?
P051D means "Crankcase Pressure Sensor A Circuit High". The crankcase pressure sensor measures pressure in the crankcase ventilation (PCV) against atmosphere; Ford's EcoBoost engines use it for the disconnection check P04DB, which needs a sound sensor. It is a generic code, so it means the same on every make.
Is it safe to drive with P051D?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P051D fail an emissions test?
Yes, it can. P051D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P051D to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P051D clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.